188 Prof. Draper on the Cause of the 



Physiologists have never given a full value to the facts, that 

 the setting of the blood requires time and a free communica- 

 tion through all parts of the fluid mass. If it be subjected 

 incessantly to a mechanism which divides it into portions of 

 inconceivable tenuity, and every moment isolates each particle 

 from all its fellows, its coagulation must be greatly restrained. 

 It is upon the same principle that the expressed juices of car- 

 rots and turnips deposit a fibrinary clot, as M. Liebig and 

 others have observed. Whilst they are enveloped in the cells 

 of those vegetables coagulation cannot take place, for each 

 granule of fibrine is shut out from the others. What need is 

 there to resort to a vital principle to explain for the human 

 ceconomy a result which equally obtains in the case of those 

 humble plants, or why with some physiologists impute to the 

 nervous system the quality of maintaining fluidity in the blood? 

 These vegetables have no nerves. 



The application of the principles here set forth furnishes a 

 very felicitous explanation of a great number of effects which 

 we witness, to some of which I may briefly refer. It is well 

 known that after ordinary death, whilst the arteries are empty, 

 the systemic veins and also the right cavities of the heart are 

 full of venous blood. The reason is clear, although the ordi- 

 nary theory, that the heart acts like a pumping machine, fails, 

 as is well known, to explain it. As long as arterial blood is 

 deoxidizing it will move to the venous side, a movement which 

 must continue until the arteries are empty. 



But it may be asked, why do not the right auricle and ven- 

 tricle relieve the veins, and by their hydraulic action in the 

 last moments of life push the accumulating blood through the 

 pulmonary system ? Again the reason is clear. Movement 

 through the lungs cannot take -place except when oxidation is 

 going on. The systemic capillaries continuing their action 

 long after the last breath is drawn, they make the blood 

 accumulate in the veins, and from them there is no escape. 



In the same way, in fainting, the blood leaving the arteries 

 accumulates on the venous side, and as its flow is dependent 

 on the push of the arterial blood entering the capillaries, so 

 soon as no more enters no pressure is exerted on the venous 

 trunks, and if a vein is opened there is no discharge, and 

 under such circumstances hemorrhages at once stop. 



After ordinary death, although the systemic arteries are 

 empty, the pulmonary artery is full. That this should be the 

 case is indicated upon our principles, for the blood cannot 

 pass from the terminal ramifications of the pulmonary artery 

 into the veins except by being oxidized. Respiration having 

 ceased oxidation cannot take place, the movement is checked, 

 and the blood remains in the artery. 



